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Cave / Cavern Benchmarks Found


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Whohoo!!! i found a list of benchmarks i had recieved after a nice conversation with a ranger & chief of program services. This past summer while touring Mammoth cave in KY, i stumbled (really did tumble over one) over two benchmark disks seated in the surface of cave ledges. Since it was dark and I wasnt expcting to see the disks "down under", i asked a ranger if they were indeed geodetic survey disks - and he confirmed that they were. I noted my location and asked the chief of program services for the actual coords for the 2 disks found, and they were provided, as well as a list of ALL benchmarks in the cave system. :unsure: how cool!! unfortunately, none of the disks are listed online for logging :rolleyes:


anyone else been able to log cave or cavern benchmarks? or any other odd locale?

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If they are not listed online for logging, then they do not belong to the National Geodetic Survey, and as such were not set for Geodetic purposes. However they may have been set by a different agency such as the US Geological Survey (USGS) and the data for them may be Geologic or Topo and belong to them.


It sounds like a very cool find. Certainly a very unique place to find survey markers. I know a lot of folks would enjoy seeing and hearing more.





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When we went to the caves, we didn't expect to see any benchmarks, so we didnt bring a pen/paper/camera. I had an old Polaroid digital cam with a whopping 2MB memory card (so i didn't even think about taking it into the cave - too bad, though)!!!


We took a 4 mile trip through Mammoth cave, and I litterally stumbled into the first ledge, about thigh high, and then during a break i asked a ranger about it to be sure that i wasn't hoping for something more. That was about 10 minutes after leaving the Snowball room. The ranger confirmed that it was a benchmark disk, but he didnt know much more about it. About 20 minutes after that (at this point I was looking for the disks), i found another about chest-high for me (i'm 5'3") at Mt. McKinley. After the tour, I cam home to ohio & wrote to the chief of program services; telling her my position, i asked for the coordinates. Of course i had to explain the whole benchmarking thing, but after getting 'clearance', she promply mailed a large packet of info to my home that contained not only the coordinates of where i was, but also the coordinated of all survey markers in the enitre cave system!!! The markers were remarkable - especially since the cave was surveyed in 1933!! Imagine in 1933 - being underground, in cold, low-light and unfamiliar areas - being able to conduct accurate measurements of distance in horizontal and vertical measurements. What a feat! There is no hope, even now, for a cell signal or satilite signal, so underground we are not really technologically advanced.

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I took a picture of a cave survey mark in Carlsbad Cave. It's a lousy picture, but I posted it with CW0761 anyway. I wished I'd taken an 'area view' for it. If anyone else visits the cave, the mark is on the floor in front of a bench by the restrooms in the Lunchroom.


I spent several years surveying caves. Set lots of stations in them, took measurements with compass, tape, clinometer, drew sketches, took notes and worked on the least squares adjustment of the data and took a bunch of pictures.


There may not be such high technology with the in-cave surveying equipment, but the computer modeling from the survey data is extremely technological and state-of-the-art, as one can see with a few internet searches. By the way, surveying hasn't stopped in Mammoth Cave - 360 miles and counting!

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